Virulência de micro-organismos à Plutella xylostella (L.) (Lepidoptera: Plutellidae) e compatibilidade com inseticidas

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

Seletividade de inseticidas a alguns dos inimigos naturais na cultura do algodão

The aim of this work was study the selectivity of insecticides in favor of natural enemies in cotton (Gossypium hirsutum latifolium Hurtch Lr), DeltaOpal cultivar, in the city of Malhada (BA), and to know the associated beneficial fauna. The study was conducted at the agricultural year of 2010/2011. The design was conducted in randomized blocks with six treatments and four replications. The treatments were: (1) Fipronil 200 SC (0.38 L.ha-1); (2) Alphacypermethrin 100 SC (0.30 L.ha-1), (3) Lufenuron 50 EC (0.30 L.ha-1), (4) Imidacloprid 200 SC (0.30 L.ha-1), (5) Methyl parathion 600 EC (1.00 L.ha-1), and (6) control (water). The product was applied 80 days after emergence, and the evaluations were performed one day before application and 1, 7 and 14 days after application (DAA). The samples were taken using the sampling method beating cloth and Moericke traps. Natural enemies were brought to the laboratory for sorting, counting and identification by family. The toxicity of the products ranged according to the group of natural enemies. Imidacloprid is selective to the spiders and insecticides are moderately toxic (Methyl Parathion and Alphacypermethrin: 1 and 14th DAA; Lufenuron: 14th DAA) or toxic (Fipronil and Alphacypermethrin: 7th DAA). Fipronil (1 DAA), Alphacypermethrin (7th DAA) and Methyl  Parathion (14th DAA) are moderately toxic to adult ladybirds. The analyzed insecticides are toxic to the larvae of ladybirds, with more impact until seven days after the application, with the exception of Methyl Parathion classified, as innocuous until this period. The occurrence of 13 families of spiders and 18 families of parasitic Hymenoptera is registered in cotton agroecosystems in the region of Malhada, in the state of Bahia.

Resisting infection by Plasmodium berghei increases the sensitivity of the malaria vector Anopheles gambiae to DDT

BACKGROUND The evolution of insecticide resistance threatens current malaria control methods, which rely heavily on chemical insecticides. The magnitude of the threat will be determined by the phenotypic expression of resistance in those mosquitoes that can transmit malaria. These differ from the majority of the mosquito population in two main ways; they carry sporozoites (the infectious stage of the Plasmodium parasite) and they are relatively old, as they need to survive the development period of the malaria parasite. This study examines the effects of infection by Plasmodium berghei and of mosquito age on the sensitivity to DDT in a DDT-resistant strain of Anopheles gambiae. METHODS DDT-resistant Anopheles gambiae (ZANU) mosquitoes received a blood meal from either a mouse infected with Plasmodium berghei or an uninfected mouse. 10 and 19 days post blood meal the mosquitoes were exposed to 2%, 1% or 0% DDT using WHO test kits. 24 hrs after exposure, mortality and Plasmodium infection status of the mosquitoes were recorded. RESULTS Sensitivity to DDT increased with the mosquitoes' age and was higher in mosquitoes that had fed on Plasmodium-infected mice than in those that had not been exposed to the parasite. The latter effect was mainly due to the high sensitivity of mosquitoes that had fed on an infected mouse but were not themselves infected, while the sensitivity to DDT was only slightly higher in mosquitoes infected by Plasmodium than in those that had fed on an uninfected mouse. CONCLUSIONS The observed pattern indicates a cost of parasite-resistance. It suggests that, in addition to the detrimental effect of insecticide-resistance on control, the continued use of insecticides in a population of insecticide-resistant mosquitoes could select mosquitoes to be more susceptible to Plasmodium infection, thus further decreasing the efficacy of the control.

THE ESTROGENIC PROPERTIES OF O,P'-DDT

o,p'-DDT is a major component of the pesticide DDT (dichlorodiphenyltrichloro ethane, technical grade). Although possessing little insecticidal ability, the o,p'- isomer has two major biological activities which affect mammalian reproductive systems: it is estrogenic, and it induces hepatic mixed function oxidase enzymes. The focus of this work is the characterization of the estrogenic properties of o,p'-DDT in rodents.^ Initial studies examined the ability of o,p'-DDT to bind to and interact with elements of the estrogen receptor system. In an in vitro assay, DDT was shown to compete with 17(beta)-estradiol (E(,2)) for binding to cytoplasmic estrogen receptors (R(,c)) from normal and neoplastic tissues in two rodent species. The following phenomena were studied by measuring receptor levels from uteri (whole uteri and/or uterine cell types) taken from immature ovariectomized rats given one acute injection of o,p'-DDT or E(,2): the translocation of the R(,c) to the nucleus, nuclear receptor (R(,n)) retention patterns, and the subsequent reappearance of R(,c) in the cytoplasm.^ The magnitude and temporal patterns of the biological responses of uteri from similar immature rats were compared following o,p'-DDT and E(,2) exposure. The responses examined included increased "Induced Protein" synthesis (in vitro); and uterine wet weight, DNA synthesis and mitosis (in vivo).^ From dose-response data, correlations were made between R(,n) levels and levels of subsequent biological responses. The aim was to lend support to the premise that biological responses to o,p'-DDT exposure occur as a result of its interaction with the classical estrogen receptor system. Correlation coefficients of 0.95 to 0.98 were obtained between R(,n) levels and levels of responses examined, strongly supporting this hypothesis.^ Finally, o,p'-DDT was shown to be as effective as E(,2) in supporting the growth of a transplantable estrogen-responsive mammary tumor in adult rats (although it was unable to support the growth of a transplantable estrogen-dependent renal tumor in hamsters). While the positive result cannot be directly extrapolated to human or animal exposure to environmental estrogens, it suggests that hyperplastic responses of estrogen sensitive tissues should be considered as a possible toxicity of o,p'-DDT, related compounds having estrogenic properties, and other environmental estrogens. ^

A literature review of the use of DDT to fight malaria

Background. First synthesized in 1874, dichlorodiphenyltrichloroethane (DDT) was not used until the second half of World War II after its insecticidal properties were discovered in 1939. For decades DDT has been used globally with the intent of eradicating malaria. This began in 1955 when the eighth World Health Assembly launched a global campaign selecting DDT as the chemical of choice for the eradication of malaria. The United States banned DDT use in 1972 partially due to the publication of “Silent Spring” by Rachel Carson in 1962 which suggested that DDT was harmful to the environment, wildlife and is a carcinogen. ^ Objectives. To critically review the literature on DDT, and evaluate its importance in malaria prevention and control. Methods: The design of this systematic literature review is a narrative summary and evaluation of the papers reviewed. The data came from searches using PubMed and MEDLINE which are free and publicly available databases. Inclusive criteria that were considered during the search are English language peer reviewed journal articles published in the last 20 years. The keywords were: “insecticidal and agricultural use of DDT”, “human impact of malaria”, “economic impact of malaria”, “benefits of DDT”, “effects of DDT”, “importance of malaria control”, and alternatives to DDT for malaria control. ^ Results. Malaria continues to be one of the most common infectious diseases and creates a tremendous global public health problem. WHO recommends DDT for malaria vector control because compared to other pesticides, it is the most persistent in indoor spraying. ^ Conclusion. Indoor spraying of DDT in malaria endemic areas may cause increased exposure of the chemical to humans; however I conclude that the overall benefits outweigh the risks because more lives are saved due to fewer infections with malaria.^

Concentrations of PCBs, DDT and thyroid hormones in gray (Halichoerus grypus) and ringed (Phoca hispida) seals

The high levels of polychlorinated biphenyls (PCBs) and DDT in gray seal (Halichoerus grypus) and ringed seal (Phoca hispida botnica) in the Baltic Sea have been associated with pathological disruptions, including bone lesions and reproductive failures. The underlying environmental and toxicological mechanisms leading to these pathological changes are not yet fully understood. The present study investigated the relationship between the individual contaminant load and bone- and thyroid-related effects in adult gray seals (n = 30) and ringed seals (n = 46) in the highly contaminated Baltic Sea and in reference areas (Sable Island, Canada, and Svalbard, Norway). In the gray seals, multivariate and correlation analyses revealed a clear relationship between circulating 1,25-dihydroxyvitamin D3 (1,25(OH)2D), calcium, phosphate, and thyroid hormone (TH) levels and hepatic PCB and DDT load, which suggests contaminant-mediated disruption of the bone and thyroid homeostasis. Contaminants may depress 1,25(OH)2D levels or lead to hyperthyroidism, which may cause bone resorption. In the ringed seals, associations between circulating 1,25(OH)2D, THs, and hepatic contaminants were less prominent. These results suggest that bone lesions observed in the Baltic gray seals may be associated with contaminant-mediated vitamin D and thyroid disruption.

Exposição a substâncias organocloradas em São Paulo: níveis séricos em doadores de sangue e fatores associados

A utilização de pesticidas organoclorados é motivo de preocupação das entidades ligadas à área de saúde em todo o mundo. Apesar de as formas de contaminação serem bem conhecidas, não há um controle eficaz na fiscalização do seu uso no Brasil. Sabe-se que altos níveis séricos destes compostos nos organismos de seres humanos e animais acarretam sérios problemas de saúde. Tendo em vista essa realidade, foi realizado, em 2009, o Projeto Piloto do I Inquérito Nacional de Populações Expostas a Substâncias Químicas, cujo subprojeto \"doadores de sangue\" teve como objetivo mensurar as concentrações de substâncias químicas no sangue de 547 residentes da região metropolitana de São Paulo, dentre elas os pesticidas organoclorados. Este trabalho teve como objetivos avaliar as concentrações dos pesticidas hexaclorobenzeno (HCB), alfa-HCH, ?-HCH, beta-HCH, beta-HCH, heptacloro, heptacloro epóxido, dieldrin, mirex, o,p\'-DDT, p,p\'-DDT, o,p\'-DDE, p,p\'-DDE, o,p\'-DDD e p,p\'-DDD nesta população e compará-las com as encontradas em outros países e determinar fatores associados aos níveis mais elevados destas substâncias. O método analítico utilizado foi de cromatografia a gás. Os resultados deste estudo indicam que a população adulta de São Paulo não está exposta a níveis preocupantes de pesticidas organoclorados, pois dentre os compostos analisados, apenas o beta-HCH e o p,p\'-DDE tiveram um número significante de amostras acima do limite de quantificação, 10,7% e 31,2% das amostras respectivamente. Quando utilizada a metade do limite de quantificação para substituir os valores abaixo do limite de quantificação do método, o valor médio encontrado para o beta-HCH foi de 0,028 ug/dL e para o p,p\'-DDE foi de 0,045 ug/dL. Este estudo propôs dois modelos multivariados para explicar os fatores associados aos compostos beta-HCH e p,p\'-DDE no sangue dos doadores. Segundo o modelo de Regressão Logística Ordinal Multivariado, os fatores associados a níveis mais altos de beta-HCH foram ter idade entre 26 e 45 anos e ser do sexo feminino. Para o p,p\'-DDE os fatores associados a níveis mais altos foram ter idade entre 26 e 45 anos, ser do sexo feminino e ter trabalhado com pesticidas, enquanto receber renda mensal de 3 a 5 salários mínimos e consumir derivados de origem animal uma ou mais vezes por semana foram associados a níveis mais baixos de p,p\'-DDE. Segundo o modelo de Regressão Linear Múltipla, os fatores associados a níveis mais altos de beta-HCH foram o sexo feminino, ter contato prévio com pesticidas na região agrícola, ter trabalhado com pesticidas em campanhas de saúde pública, ter trabalhado em empresas de capacitores ou transformadores, ter trabalhado em indústrias de solventes clorados, ter renda mensal de 3 a 5 salários mínimos, consumo de carnes uma ou duas vezes por semana e consumo de frutos do mar uma ou duas vezes por semana, enquanto consumo frequente de cerveja e ter renda mensal de 1 a 3 salários mínimos foram associado a níveis menores de beta-HCH. Já para o p,p\'-DDE, os fatores associados a níveis mais elevados foram ser do sexo feminino, ser não branco, ter trabalhado com pesticidas e consumir água de fontes que não sejam minerais ou de rede, enquanto o consumo frequente de bebidas alcoólicas foi associado a níveis mais baixos de p,p\'-DDE

Ambient water quality criteria for DDT /

Mode of access: Internet.

Special occupational hazard review for DDT.

"September 1978."

DDT in the diet of the rat; its effect on DDT storage, liver function, and cell morphology

Bibliography: p. 26-27.

Studies on the effects of DDT on birds.

Mode of access: Internet.

A preliminary study of the influence of Velsicol AR-60 upon the insecticidal effectiveness of dusts containing rotenone or DDT.

"Literature cited": leaf 84.

Effect of DDT on Amphimallon majalis beetles.

Typewritten.

DDT and other insecticides and repellents developed for the armed forces /

"Interim report no. 0-100 (NRC Insect control committee Report no. 100). A report to the Committee on medical research on work done under a transfer of funds, recommended by this committee, from the Office of scientific research and development to the Bureau of entomology and plant quarantine."--Foot-note, p. 1.